What Causes Eye Floaters?
There are two main types of eye floaters, and the two have very different causes. Eye floaters are classified as either benign or pathological, with the former being the most prevalent type. There is no way of telling whether you have benign or pathological eye floaters, and therefore, you should visit a qualified health professional as soon as you develop the eye floaters and again whenever you notice a drastic change in the number or severity of the floaters.

To understand the causes of eye floaters, first you need to understand the basic eye anatomy. The eye is filled up with transparent jelly-like liquid, called the vitreous humor. This liquid is about 99% water and 1% protein. The vitreous humor is attached to the eye at the optic nerve head (found in the posterior part of the eye) and at the anterior part of the eye orbit. However, separation of these attachment points is fairly common, and may occur as a result of injury to the eye, strenuous exercise, or for no particular reason. The detachment of the vitreous humor from posterior part is the most common cause of benign eye floaters. When this gel-like solution is detached, it will now be free to move around and sometimes it will make contact with the retina. When this happens, the person will see flashes, called photopsias.

When the vitreous humor is free to move, it progressively becomes less transparent because the proteins tend to aggregate together. These aggregates give rise to floaters, technically called vitreous syneresis. It is estimated that over half of the world's population will develop eye floaters at some point in their lives and they can occur at any age, although they are more common in older adults.

The other type of eye floaters is the pathological one. In this case, there is a similar detachment of the vitreous humor, however, it occurs from the anterior attachment. When this happens, the retinal tissues may get pulled to such an extent so as to create a hole in the retina. As a result, some blood can leak into the eye cavity, and this gives rise to eye floaters. This type of eye floaters can be very dangerous, because if it is left unattended, total retinal detachment can occur. This will require surgery to be corrected, and it can lead to blindness if it is not treated.

There are other conditions and circumstances that can cause blood to leak into the eye cavity, the most common of which is proliferative diabetic retinopathy, a fairly common condition in diabetics who do not manage their condition properly. What happens in this case is that abnormal blood vessels will grow in the retina, and these may bleed into the vitreous humor. Other conditions that can give rise to eye floaters include macular degeneration, foreign bodies that end up in the eye, and some parasites.